A round, yellow sign with "RR" and a smaller sign reading "EXEMPT" indicates what?

The round, yellow sign displaying "RR" alongside a smaller sign that reads "EXEMPT" indicates that the driver is approaching a railroad crossing where a stop is not mandatory when a train is approaching. This specific signage is often used for certain vehicles transporting materials that qualify for an exemption, such as certain types of freight trains or vehicles passing through the crossing that aren't subject to the standard stopping requirements.

In most cases, drivers are required to stop when they see a railroad crossing sign, but the "EXEMPT" designation allows for some flexibility depending on the nature of the vehicle or cargo. This means that while caution and vigilance are still necessary as trains may come through, the driver has the option to proceed without stopping if conditions are clear and no train is present.

The other options suggest more stringent stopping requirements, which do not apply in situations where "EXEMPT" is indicated, as that sign significantly alters the usual rules associated with railroad crossings.